Let's Go Shopping! (Part I)

Imagine for a moment that your church’s administrator has just come to you to announce that the church board has granted permission for you to buy a new sound mixing console for the front-of-house desk. Once you’ve picked yourself up off the floor, you run straight to your local pro audio store to see what’s available before the board changes their mind.

With a thousand and one choices for consoles out there these days, the question turns to defining your needs for the console so you can narrow your search. What do you really need, versus what will do the job? What bells and whistles are actually worth having?
Let’s put together a checklist of features commonly available on consoles today. Then you can use that list to go shopping for the right console for your house of worship.

Channels

Mic/Line Inputs – You probably already have a good idea about the number of inputs you’ll need on a new console, based on your current worship team. “More than I have now” is probably not the best response. Remember to include all of the source decks you have or want to add, like cassette decks, MiniDisc players, CD players, and so on. Also consider the extra inputs that you’ll need during major productions, music pageants and dramas. Removable I/O (input/output) modules would be great for servicing, but they’re rarely seen anymore even on higher-priced live sound consoles.

Take a close look at the fine print regarding the number of inputs that the console has. Many consoles offer stereo channels in addition to the standard I/O modules. The stereo channels occupy a single channel slot, but will accept a left and right input. The fader at the bottom of the module is a stereo fader. So if the console literature says that it has 24 inputs, you need to dig a little deeper to find out if those are 24 mic/line inputs, or if there are actually only 16 mic/line inputs plus four stereo line level inputs. Most consoles provide separate connectors on the back of the console for mic level or line level inputs. The line level input may or may not be a balanced (low impedance) input.

Trim/Gain – The trim controls the gain of the mic preamp, allowing you to adjust for the sensitivity of different microphones as well as the strength of various incoming sound sources being picked up by those mics. All consoles with a mic input have a mic preamp built-in, but some small mixers preset the gain of the preamp for you. The trim is a given on any console larger than about eight channels.

100mm faders – From this day forward, don’t call them sliders anymore. We want you to be hip, and if you’re going to be hip while driving a console, you’ve got to call them faders. Faders with a 100mm throw (a little less than four inches) give you more room to make fine adjustments to your mix than faders with a shorter throw.

PFL/AFL – These stand for Pre-Fade Listen, and After-Fade Listen. Other common terms for the PFL feature are Solo and Cue. This is primarily a troubleshooting feature that allows the operator to isolate a particular channel, subgroup, or auxiliary send, and listen to only that feed over a set of headphones. It’s great for finding bad mic cables, out-of-tune vocals, and other problems. Let’s say that you have a mic cable that’s going bad during the worship set. Using the PFL, you can quickly isolate which channel is causing the problem so you can call your assistant on stage – you do have an assistant on stage, right? – and ask them to replace the cable. The signal for the PFL is picked off before the channel fader, and on many consoles you can pull down the fader so the offending sound doesn’t go to the house system, and yet still listen to the input so you’ll know when the problem has been corrected. The signal for the AFL is picked off after the channel fader, so you can expect to hear any EQ changes you make on that channel.

Prefade Auxiliary Sends – Most of the audio engineers that I know feed the stage monitors and headphones from a prefade auxiliary send. Another term is foldback, suggesting that you’re bringing the signal in from the stage on the mic line, and then you’re folding it back to the performer’s stage monitors. A prefade send allows you to make any adjustment you need to the house mix without affecting their monitor mixes. If you’re mixing the monitors and headphone feeds from the house desk, then look for all the prefade aux sends you can get your hands on. It used to be that all prefade sends were picked off before the EQ circuit, but lots of consoles today allow any channel EQ adjustments that you make for the house mix to also be heard in the aux sends feeding the stage monitors. I’m not entirely sure that’s a good thing, because it can lead a singer or player on stage to ask me to adjust their channel EQ based on what they’re hearing over their stage monitors, which has little comparison to the sound I’m hearing over the house loudspeaker system. Your call.

Postfade Auxiliary Sends – A postfade auxiliary send is typically used to feed an effects device. Whenever possible, I like to have a least three postfade auxiliary sends that I can dedicate to the effects sends. I like to use two different reverb units, one for the worship band and another for the vocals, with the third send feeding a digital echo device. The feed is picked off after the channel EQ and after the channel fader. I like to have a fourth postfade send to feed the subwoofer system. That lets you dial up how much signal you want to feed to the subs from the drum channels, the bass guitar, synthesizers, and other appropriate inputs, while not feeding any signal from vocal mics, choir mics, flute or brass mics, and so on. That allows you to deliver a clean, solid mix with plenty of weight to the sound.

Parametric EQ – A parametric EQ gives you control over the bandwidth, the amount of boost/cut, and a sweepable frequency. It’s wonderful to have that much EQ flexibility. In a perfect world, we’d ask for parametric controls on each band of each channel EQ.

Sweepable EQ – It bothers me to see the term quasi-parametric in console literature. To me, that’s like saying someone is sort of pregnant. It’s either parametric, or it isn’t. A sweepable EQ allows you to sweep a range of frequencies and lock onto the specific area you need to improve the sound on each channel. Even with a preset bandwidth, that’s quite powerful compared to the alternative of a fixed EQ frequency.

Fixed Frequency EQ – This is the least user friendly of all EQ choices, at least for midrange frequencies. Here the manufacturer has pre-selected one or two frequencies that they believe are appropriate for your use, and you’re stuck with them. Let’s say that the midrange EQ is preset for 2 kHz, but you need to make an adjustment at 5 kHz to help the sound of someone’s voice. You’re out of luck with this type of EQ.
A reasonable compromise is to have a fixed EQ for the high frequency control as well as the low frequency control, and then have a fully parametric EQ for one or two midband frequency sections. That allows you lots of control in the midrange frequencies where our hearing is most sensitive. If you can’t afford the fully parametric (there they go again) feature, then at least go for the sweepable midrange frequencies.

Channel Mute – A cool name for the On/Off Switch on each channel. Look for a console that places the channel mute early in the signal flow, like right after the mic preamp. What you want is for the channel mute to turn off both the signal to the fader as well as the signal to all of the aux sends. When you mute the channel, it’s muted everywhere, including the stage monitors and effects sends.

48V Phantom Power – This is pretty much standard on consoles today. Condenser mics require a DC voltage to power their internal preamp and provide a polarizing voltage for the capsule. The simplest way to provide that is via the phantom power supply on a console. It feeds 48V DC voltage on pins 2 and 3 of a mic cable, referenced to the ground on pin 1.

HPF – The letters stand for high pass filter. You could also call it a low frequency cut filter. Some consoles have a switch labeled HPF which inserts a low frequency cut at a pre-selected frequency, while some have a sweepable HPF control. All frequencies below that pivot frequency are attenuated. Using a HPF will help you clean up your mix dramatically, keeping muddy, low frequency sounds from being amplified through vocal mics, and so on. It will keep you from taxing the available headroom of the system, which can lead to system distortion prematurely.

Direct Outs – There are two specific ways that having a direct output on each channel has proven useful for me in the past. One is to feed the output of a specific channel to a multitrack recorder. Recording consoles have a similar feature, and recording of live performances has become so common these days that it’s no surprise that manufacturers started adding that feature to their live sound consoles. Another use would be to feed a specific channel to a personal monitor mixing system. For example, many of the churches that I’m consulting with these days like the idea of having personal monitor mixers on stage for the players. That often involves a small mixer, with maybe eight to sixteen channels, for each player. We might submix all of the drums and use the subgroup output to feed an input on the personal monitor mixer, and maybe do the same for all of the keyboards on another channel. But single elements like the bass guitar, or the worship leader, are better off being fed from the direct output on a channel.

Insert Patchpoint – Also known as a send/return patchpoint, this feature allows you to insert, for example, a compressor on only the worship leader’s vocal mic. The patchpoint is typically picked off early in the signal flow of the channel, often right after the mic preamp. Many consoles provide insert patchpoints on each individual channel and on each of the subgroups. A patchpoint on the subgroup would allow you insert a compressor, for example, on the backing vocal subgroup. Most consoles provide the insert patchpoint on a TRS jack, with the tip being the positive conductor feeding to the input of the device you’re connecting, and the ring being the positive conductor receiving the output of the device you’re connecting, with the shield being the ground connection for both. In other words, it’s an unbalanced connection. If your budget allows, look for separate, balanced connections for the send and return on each channel.

That’s all for now, make sure you read the next issue for more items to consider when shopping around.

Curt & Jeanna Taipale are the founders of the ChurchSoundcheck Discussion Group and web site www.churchsoundcheck.com Their consulting firm, Taipale Media Systems, Inc., specializes in the design of performance systems and acoustics for houses of worship. Curt is also an author and educator, and periodically offers training for church tech support staff and volunteers. Curt can be reached via email at curt@churchsoundcheck.com. This article was first published in the March/April 2001 issue of Live Sound International. www.livesoundint.com